Vehicle pedal assembly including a hysteresis feedback device

ABSTRACT

An electronic adjustable control pedal assembly for a motor vehicle including a carrier, a guide rod adapted to be secured to the dash panel of the vehicle and mounting the carrier for fore and aft movement along the guide rod, a power drive operative to move the carrier along the guide rod, and a pedal structure including a pedal arm pivotally mounted on the carrier and a potentiometer mounted on the carrier and operative to generate an output electrical signal proportioned to the extent of pivotal movement of the pedal arm. The pedal assembly further includes a feedback apparatus for generating a feel in response to pivotal movement of the pedal arm. The feedback apparatus includes a spring to exert a spring force against the pedal arm that varies in response to the pivotal movement of the pedal arm, a first friction surface on the pedal arm, and a second friction surface on the spring for wiping coaction with the first friction surface in response to the pivotal movement of the pedal arm to provide a hysteresis effect for the pedal assembly.

RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.08/516,050, filed Aug. 17, 1995, now U.S. Pat. No. 5,819,593, which is aContinuation-In-Part of U.S. application Ser. No. 08/513,017, filed Aug.9, 1995, now U.S. Pat. No. 5,632,183.

BACKGROUND OF THE INVENTION

This invention relates to control pedal apparatuses and moreparticularly to adjustment means for selectively adjusting the positionof one or more of the control pedals of a motor vehicle.

In a conventional automotive vehicle pedals are provided for controllingbrakes and engine throttle. If the vehicle has a manual transmission aclutch pedal is also provided. These pedals are foot operated by thedriver. In order for the driver to maintain the most advantageousposition for working these control pedals the vehicle front seat isusually slidably mounted on a seat track with means for securing theseat along the track in a plurality of adjustment positions.

The adjustment provided by moving the seat along the seat track does notaccommodate all vehicle operators due to differences in anatomicaldimensions. Further, there is growing concern that the use of seattracks, and especially long seat tracks, constitutes a safety hazard inthat the seat may pull loose from the track during an accident withresultant injuries to the driver and/or passengers. Further, the use ofseat tracks to adjust the seat position has the effect of positioningshorter operators extremely close to the steering wheel where they aresusceptible in an accident to injury from the steering wheel or from anexploding air bag. It is therefore desirable to either eliminate theseat track entirely or shorten the seat track to an extent that it willbe strong enough to retain the seat during an impact. Shortening oreliminating the seat track requires that means be provided toselectively move the various control pedals to accommodate various sizedrivers.

Various proposals were made over a period of many years to provideselective adjustment of the pedal positions to accommodate various sizedrivers but none of these proposals met with any significant commercialacceptance since the proposed mechanisms were unduly complex andexpensive and/or were extremely difficult to operate and/or accomplishedthe required pedal adjustment only at the expense of altering othercritical dimensional relationships as between the driver and the variouspedals. Recently a control pedal mechanism has been developed which issimple and inexpensive and easy to operate and that accomplishes therequired pedal adjustment without altering further critical dimensionalrelationships as between the driver and the various pedals. This controlpedal mechanism is disclosed in U.S. Pat. Nos. 4,875,385; 4,989,474 and5,078,024 all assigned to the assignee of the present application. Thepresent invention represents further improvements in adjustable controlpedal design and specifically relates to an adjustable control pedalapparatus which is compatible with, and incorporates, a drive-by-wirearrangement in which the link between the pedal and the associatedcontrolled device of the motor vehicle comprises an electronic signalrather than a mechanical linkage.

SUMMARY OF THE INVENTION

This invention is directed to the provision of a simple, inexpensive andeffective apparatus for adjusting the control pedals of a motor vehicle.

More specifically, this invention is directed to the provision of anadjustable control pedal apparatus that is especially suitable for usein conjunction with a drive-by-wire throttle control.

The invention apparatus is adapted to be mounted on the body structureof the motor vehicle and includes a carrier, guide means mounting thecarrier for fore and aft movement relative to the body structure, anddrive means operative to move the carrier along the guide means.According to the invention, the pedal assembly further includes a pedalstructure mounted on the carrier for movement relative to the carrierand means operative in response to movement of the pedal structure onthe carrier to generate an electrical signal proportioned to the extentof movement of the pedal structure on the carrier. This arrangementprovides a simple and effective means of generating an electroniccontrol signal on an adjustable pedal assembly and ensures that theergonomics of the control pedal will not vary irrespective of theposition of adjustment of the pedal structure.

According to a further feature of the invention, the pedal structure ispivotally mounted on the carrier and the electric signal is generated inresponse to pivotal movement of the pedal structure on the carrier. Thisspecific arrangement retains the customary pivotal movement of thecontrol pedal and also maintains the constant ergometric operation ofthe control pedal assembly.

According to a further feature of the invention, the generator meansincludes a potentiometer mounted on the carrier whose setting is variedin response to pivotal movement of the pedal structure on the carrier.This specific arrangement provides a simple and effective means ofgenerating the required electronic signal to provide drive-by-wireoperation.

According to a further feature of the invention, the pedal structureincludes a pedal arm and a pedal mounted on a lower end of the pedalarm, and the pedal assembly further includes resistance means includinga leaf spring fixedly mounted at one end thereof on the carrier andhaving a free end biased against an upper region of the pedal arm so asto operate to resist the pivotal movement of the pedal structure. Thisspecific arrangement provides a simple and effective means of providingthe desired feel or feedback to the operator upon movement of the pedal.

According to a further feature of the invention, the resistance meansfurther includes a first resistance plate mounted on the upper region ofthe pedal arm and a second resistance plate mounted on the free end ofthe leaf spring and biased against the first resistance plate. Thisarrangement allows the resistance offered to the pivoting pedal to bevaried either by varying the spring characteristics of the spring or byvarying the resistance characteristics of the resistance plates.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of an electronic adjustable pedal assemblyaccording to the invention;

FIG. 2 is a fragmentary side view of the pedal assembly;

FIG. 3 is a detail view taken within the closed line 3 of FIG. 2;

FIG. 4 is an end view of the pedal assembly;

FIG. 5 is a cross-sectional view taken on line 5--5 of FIG. 1; and

FIG. 6 is a cross-sectional view taken on line 6--6 of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention control pedal assembly, broadly considered, is intended toallow efficient fore and aft movement of the pedal assembly toaccommodate operators of varying anatomical dimension and is operativeto generate an electronic or drive-by-wire signal in response to pivotalmovement of the pedal assembly while retaining the same ergometricoperation of the pedal irrespective of the position of adjustment of thepedal.

The pedal assembly includes a support structure 10, a carrier assembly12, a drive assembly 14, a pedal assembly 16, a resistance assembly 18,and a generator means 20.

Support structure 10 may be formed as two or more parts which aresuitable joined together or may, as shown, be formed as a singleintegral unitary member in a casting or forging operation. Structure 10includes a bracket portion 10a, a transmission housing portion 10b, anda guide rod portion 10c.

Bracket portion 10a is adapted to be suitably secured to the dash panel22 of the associated motor vehicle utilizing suitable fastener means inknown manner.

Transmission housing portion 10b extends rearwardly from bracket portion10a and has a generally cubicle configuration defining a hollow 10copening at the front face 10d of bracket 10a and further defining acentral bore 10e in a rear wall 10f of the housing portion.

Guide rod portion 10c extends rigidly rearwardly from the rear wall 10fof the transmission housing portion, is hollow so as to provide atubular configuration defining a central circular bore 10g concentricwith bore 10e, is open at its rear end 10h, and includes an upper axialslot 10i extending from a location proximate the transmission housingwall 10f to a location proximate guide rod rear end 10h.

Carrier assembly 12 includes a housing 24, a nut 26, and a key 28.

Housing 24 may be formed as a casting, forging or stamping, and isdesigned to move slidably along the guide rod portion 10c of supportstructure 10. Housing 24 includes a rear wall 24a, side walls 24b and24c, a bottom wall 24d, a top wall 24e, and a front wall including anupper portion 24f, a lower portion 24g, and an angled intermediateconnector portion 24h. A circular opening 24i is provided in rear wall24a proximate top wall 24e and a circular opening 24j is provided infront wall upper portion 24f proximate top wall 24e in axial alignmentwith opening 24i. Housing 24 is mounted on the guide rod portion 10c ofsupport structure 10 with guide rod portion 10c passing throughapertures 24i and 24j and bushings 30 positioned in apertures 24i and24j in sliding engagement with the outer periphery of guide rod portion10c so as to mount the housing for sliding movement along the guide rod.Angled front wall 24h is complementary to the angled lower surface 10jof the transmission housing portion 10b of support structure 10 so thatthe housing 24 may move into nesting relation with respect to thesupport structure with the housing in its extreme forward position asseen in FIG. 1.

Nut 26 is circular, is mounted for sliding movement in circular bore 10gof support structure 10, and defines a central threaded bore 26a.

Key 28 is seated at its lower end 28a in a notch 26b in the upperperiphery of nut 26 and passes upwardly through slot 10i and through anopening 24k in top housing wall 24e for securement at its upper end 28b,by fasteners 32, to a flange 241 upstanding from housing top wall 24e.Key 28 thus lockingly interconnects nut 26 and housing 24 so thatmovement of nut 26 in bore 10g is imparted to housing 24 so as to movehousing 24 axially along guide rod portion 10c.

Drive assembly 14 includes a motor 34, a cable 36, a bracket 38, a worm40, a worm gear 42, and a screw shaft 44.

Motor 34 comprises a suitable electric motor, with position memory ifrequired, and is suitably secured to dash panel 22 proximate the bracketportion 10a of the support structure.

Cable 36 comprises a well-known bowden cable and is drivingly secured atone end 36a to the output shaft of motor 34. Bracket 38 is secured to anouter face of transmission housing 10b and mounts the other end 36b ofcable 36.

Worm 40 is suitably journalled in transmission housing 10b in overlyingrelation to cavity 10c and is drivingly connected to cable end 36b.

Worm gear 42 is journalled in cavity 10c in meshing engagement with worm40 and includes a front trunion 42a journalled in a bearing 45positioned in the open front end of cavity 10c and a rear trunion 42bjournalled in a counterbore 10k in transmission rear wall 10f.

Screw shaft 44 extends rearwardly from worm gear 42 centrally withinsupport structure bore 10g and passes threadably through the threadedcentral bore 26a of nut 26.

It will be seen that actuation of motor 34 has the effect of rotatingscrew shaft 44 to thereby move nut 26 and housing 24 fore and aft alongguide rod 10c with the extent of forward and rearward movement definedand limited by engagement of key 28 with the front and rear ends of slot10i.

Pedal assembly 16 includes a pedal arm 46 and a pedal 48 secured to thelower end 46a of the pedal arm. Pedal arm 46 passes upwardly through aslot 24m in the lower housing wall 24d for pivotal mounting at its upperend 46b to housing side walls 24b and 24c via a pivot shaft 50.

Resistance assembly 18 includes a pedal arm friction cam plate 52, aleaf spring 54, and a spring friction cam plate 56. Resistance assembly18 is intended to provide feedback or "feel" to the operator to replacethe feedback normally provided by the mechanical linkage interconnectingthe pedal and the controlled device such as the fuel throttle. With amechanical linkage, the pedal pressure required when advancing theaccelerator pedal is greater than that required to maintain a fixedposition. This difference is often referred to as due to the hysteresiseffect. This effect is important in maintaining the accelerator pedal inposition while driving at a relatively constant speed and it must alsobe considered in achieving a desired deceleration time. The pressurewhich must be applied in accelerating is easily borne but if the backpressure of an accelerator spring produced the same effect during thetime it was required to retain or maintain speed it would soon becomeuncomfortable for the operator to maintain a relatively constant speed.The hysteresis effect provides relief. It lessens the load required tomaintain a setting of the accelerator yet there is still force to causereverse pedal action when the foot applied pressure is removed.Resistance assembly 18 provides the "feel" of a mechanical linkageincluding the desired hysteresis effect to relieve operator fatigue.

Pedal arm friction cam plate 52 may be formed, for example, of a Delrin®material and is secured to an upper cam edge 46c of the pedal arm via adovetail connection 52a.

Spring 54 comprises a laminated leaf spring and includes a curl 54a atits upper end wrapped around a pin 24m projecting inwardly from housingside wall 24b. A nub 24n projects inwardly from housing side wall 24bbelow pin 24m and coacts with pin 24m to trap the end tip 54b of curl54a to fixedly secure the upper end of the spring to housing side wall24b.

Spring friction cam plate 56 may be formed, for example, of a glassfilled nylon material and includes a working portion 56a suitablysecured to the lower end 54b of leaf spring 54 and a tail portion 56bpassing upwardly between the leaves 54a, 54b of leaf spring 54. Theparts are configured such that with the pedal 48 in its upper or restposition, as seen in FIG. 1, friction plate working portion 56a is urgedagainst friction plate 52 by spring 54 so as to resist pivotal movementof the pedal assembly to an operative position with the resistance beingconstituted both by the increasing resistance force of the spring 54 andby the frictional resistance force between plates 52 and 56a generatedby the wiping or camming action of plate 52 against plate 56a as thepedal arm pivots about the axis of pivot shaft 50. Upon release ofpressure on the pedal, the frictional resistance force between plates 52and 56a become subtractive rather than additive with respect to theforce of spring 54, thereby creating the desired hysteresis effect. Thematerials of cam plates 52 and may be selectively varied to selectivelyvary the friction levels and hence the damping or hysteresis effectprovided by the rubbing plates.

Generator means 20 comprises a potentiometer 60 positioned within thehollow of housing 24 and suitably secured to housing side wall 24c.Potentiometer 60 includes a central shaft, constituted by the pivotshaft 50, a housing 60a concentric with shaft 50, a plurality ofresistance elements 60b mounted circumferentially around the innerperiphery of housing 60a in side-by-side relation, a wiper arm 60cmounted on shaft 50 and operative to electrically slidably engage theresistance elements 60b in response to pivotal movement of shaft 50, andan outlet 60d projecting rearwardly through opening 24p in housing rearwall 24a and electrically connected to wiper 60c and resistance elements60b in a manner such that the electrical signal appearing at the outlet60d varies In proportion to the extent of pivotal movement of the pivotshaft 50. It will be seen that pivotal movement of pedal 48 has theeffect of rotating pivot shaft 50 and thereby varying the electricalsignal appearing at the potentiometer outlet 60d so that the signalappearing at outlet 60d is at all times proportioned to and indicativeof the pivotal position of the pedal. It will be understood thatelectric power is suitably supplied to potentiometer 60 and anelectrical conduit 62 is suitably connected to potentiometer outlet 60dand extends to the vehicle function or accessory, such as the vehiclethrottle, that is being electrically controlled by the pedal assembly.

In operation, the position of the pedal 48 relative to the operator isselectively adjusted by selectively energizing motor 34 to selectivelymove nut 26 forwardly and rearwardly within guide rod bore 10g andthereby, via key 28, move the pedal assembly selectively forwardly andrearwardly along guide rod 10c with the limits of forward and rearwardmovement determined by engagement of the key with the respective forwardand rearward ends of the slot 10i. In any position of adjustment of thepedal, actuation of the pedal or release of the pedal results, in themanner previously described, in the generation of an output signal atthe outlet 60d proportioned to the extent of pivotal movement. Since thepivotal movement of the pedal arm is precisely the same in any positionof adjustment of the pedal structure, the ergometrics of the assembly donot vary irrespective of the position of adjustment of the pedalassembly and irrespective of the anatomical stature of the operator.

As the pedal is moved downwardly, a "feel" is imparted to the pedal,simulating the feel of a mechanical linkage between the pedal and thecontrolled vehicle system, by the combined effect of flexing of the leafspring 54 and frictional sliding or wiping engagement between thefriction plates 52 and 56a. Further, as the pedal is released or allowedto return, the frictional force becomes subtractive rather than additivewith respect to the spring force, thereby creating the desiredhysteresis effect. The amount of feel imparted to the pedal can thus beprecisely adjusted by adjusting the spring rate or other parameters ofleaf spring 54, and/or by adjusting the materials or other parameters offriction plates 52 and 56, and/or by adjusting the rise of cam edge 46c,thereby rendering it relatively easy to fine tune the system to achieveany desired feel and any desired hysteresis effect.

The invention will be seen to provide an electronic adjustable pedalassembly for a motor vehicle in which the assembly may be readilyadjusted to accommodate operators of varying anatomical dimensions andin which the ergometrics of the system remain constant irrespective ofthe position of adjustment of the pedal structure.

Whereas a preferred embodiment of the invention has been illustrated anddescribed in detail, it will be apparent that various changes may bemade in the disclosed embodiment without departing from the scope orspirit of the invention. For example, although the invention pedalassembly has been indicated for use in controlling the throttle of theassociated vehicle, the invention pedal assembly may be used toelectrically control a wide variety of vehicle functions or accessories.Further, although the resistance assembly 18 has been illustrated asproviding the damping for an adjustable pedal assembly, it will beapparent that this resistance assembly can also be utilized to providedamping for a non-adjustable pedal assembly.

We claim:
 1. A control pedal assembly adapted for use on a motor vehicleincluding a pedal arm pivotally mounted at one end thereof to a supportstructure mounted on the motor vehicle and a feedback apparatus forgenerating a feel in response to pivotal movement of the pedal arm,characterized in that the feedback apparatus comprises:a spring mountedon the support structure and arranged to exert a spring force againstthe pedal arm that varies in response to pivotal movement of the pedalarm; a first friction surface defined by a first friction plate securedto the pedal arm; and a second friction surface defined by a secondfriction plate secured to the spring and arranged for wiping coactionwith the first friction surface in response to pivotal movement of thepedal arm.
 2. A pedal assembly according to claim 1 wherein:the frictionsurfaces undergo relative wiping movement in a first direction, andgenerate a friction force augmenting the spring force, in response topivotal movement of the pedal arm in a pedal applying direction andundergo relative wiping movement in a second opposite direction, andgenerate a friction force opposing the spring force, in response topivotal movement of the pedal arm in a pedal releasing direction,whereby to provide a hysteresis effect for the pedal assembly.
 3. Apedal assembly according to claim 2 wherein:the spring comprises a leafspring fixedly secured at one end thereof to the support structure anddefining a free end; and the second friction surface is defined on thefree end of the leaf spring.
 4. A pedal assembly according to claim 3wherein:the first friction surface is defined on an upper end of thepedal arm.
 5. A pedal assembly according to claim 4 wherein said one endof said leaf spring comprises an upper end of the leaf spring and thefree end of the leaf spring comprises a lower end of the leaf spring. 6.A pedal assembly according to claim 5 wherein the first and secondfriction plates are of dissimilar materials.
 7. A pedal assemblyaccording to claim 3 wherein:the first friction surface is defined bythe first friction plate secured to an upper edge of the pedal arm; andthe second friction surface is defined by the second friction platesecured to the free end of the leaf spring for wiping engagement withthe first friction plate.
 8. A pedal assembly according to claim 7wherein the leaf spring comprises a laminated leaf spring and the secondfriction plate includes a working portion wipingly engaging the firstfriction plate and a tab portion positioned between laminations of thespring.
 9. A control pedal assembly adapted for use on a motor vehicleincluding:a support structure adapted to be mounted on a body structureof the motor vehicle; a pedal structure including a pedal arm pivotallymounted at one end thereof to the support structure on a pivot axis; acam surface defined on the pedal arm that is eccentric with respect tothe pivot axis of the pedal arm; a leaf spring fixedly secured at an endthereof to said support structure and having a free end biased againstsaid cam surface so that pivotal movement of the pedal arm generates awiping action between the cam surface and the free end of the spring andvaries the extent of flexing of the spring about its fixed end; and thecam surface is defined by a first friction plate secured to the pedalarm; and a second friction plate is secured to the free end of thespring for wiping engagement with the first friction plate.
 10. A pedalassembly according to claim 9 wherein the first and second frictionplates are of dissimilar materials.
 11. A pedal assembly according toclaim 9 wherein:the leaf spring comprises a laminated leaf spring andthe second friction plate includes a working portion wipingly engagingthe first friction plate and a tail portion positioned betweenlaminations of the spring.